Standard def STB repeatedly blacks out for a second or 2

Question

A site search on "black out" does not turn up a similar issue, of course it may be my search skills are lacking. 
New subsciber since Sep 2010.   I have 3 boxes, 2 standard QIP2500 phase 3 (basement/MBR) and 1 hi-def (LR). Hi def TV in MBR, standard in other 2.  Both standards would on occassion 'black out' for just a second or 2 ever since original install. No problem with the hi-def. One standard is wired with coax, one with s-video, the hi-def with HDMI.  When the black out occurs, the screen will freeze for an instant, then the screen goes black, then it comes back. The information on the box does not black out, the TVs don't power-off and restart. It's just the screen goes blank and then comes back. It happens without any seeming warning, and will happen at any time of day. Sometimes it will happen repeatedly, sometimes it won't happen for a long time.  Both boxes have been repeatedly reset and rebooted with no improvement.  During one tech call the tech had me relocate one of the standard boxes to the hi-def location to isolate that it wasn't a location (in-house cable) problem. I thought it curious since it was happening at 2 different locations but went through the drill anyway.  The relocated standard worked for a few minutes, then went black for a second as the problem does.  Plugging the high-def back in resolved the issue at that location. The tech said he would send 2 new standard boxes. The replacement boxes have not resolved the issue.  Any suggestions? 

Answer 1

if it's doing that on two different boxes using both coax and s-video then I think that leaves a possibility of the coax.  that would be a unusual symptom of a bad coax/splitter but try this.  
Wait for it to start acting up - when it starts acting up, stay tuned to that station, and hit your menu > customer support > in home agent > network diagnostics and click ok to start.
check the video signal using that menu selection.  after it's done running it will give you a general message like "you're video signals are not in the optimal range"     after you see that, hit info and then look at the SNR DB   it should give you a number.
32-36 is optimal, below that is questionable.
If it is below that then it's probably going to be a problem with the splitter at your house, and you would either replace it yourself, or call verizon to replace it.  be sure to tell them the DB